Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
  • G21C3/42—Selection of substances for use as reactor fuel
  • G21C3/58—Solid reactor fuel Pellets made of fissile material
  • G21C3/62—Ceramic fuel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
  • B01J2/06—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a liquid medium
  • B01J2/08—Gelation of a colloidal solution
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B32/00—Carbon; Compounds thereof
  • C01B32/90—Carbides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F15/00—Compounds of thorium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G25/00—Compounds of zirconium
  • C01G25/02—Oxides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G43/00—Compounds of uranium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G43/00—Compounds of uranium
  • C01G43/01—Oxides; Hydroxides
  • C01G43/025—Uranium dioxide
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/30—Particle morphology extending in three dimensions
  • C01P2004/32—Spheres
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/10—Solid density
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• metal salt solutions preferably, those of uranyl and/or thorium salts, which form solid compounds when introduced into aqueous alkaline precipitating baths by emulsifying the aqueous salt solution with an oil, if desired, with addition of a binding agent, introducing the emulsion in droplet form into an aqueous alkaline precipitation bath to produce solid spheres which are dried and sintered
• the invention relates to a process for the production of spherical oxidic or carbidic particles from heavy metal salt solutions.
• spherical and highly dense oxidic or carbidic particles of uranium and/or thorium or plutonium are becoming increasingly important. They can be used either as fuels for high temperature nuclear reactors in the form of coated particles or they can be used in vibration compacted fuel elements.
• Powder metallurgy processes have primarily been used in the preparation of such particles. However, in view of the reprocessing of spent nuclear fuel, chemical proce dures for the preparation of the particles are more advantageous as the solutions produced can be directly processed further.
• a simple process for the production of highly dense oxidic or carbidic particles directly from metal salt solutions, preferably those of uranium and/ or thorium, wherein the aqueous metal salt solution is emulsified with an oil with the aid of an emulsifier and thereby split up into extremely fine droplets and, if desired, after addition of a binding agent, such emulsion is introduced in the form of droplets into an alkaline medium whereby solid spheres are produced (gelation) which are dried and sintered.
• a binding agent such emulsion is introduced in the form of droplets into an alkaline medium whereby solid spheres are produced (gelation) which are dried and sintered.
• graphite or carbon black is also suspended in the emulsion before it is introduced to the alkaline medium.
• the process according to the invention is especially suited for the treatment of aqueous nitrate solutions of hexavalent uranium but also is suited for treatment of other aqueous solutions of metal salts which form solid compounds when introduced into an alkaline media, such inc as, for instance, zirconium or aluminum.
• the salts employed may, for example, be the chlorides, oxychlorides, fluorides or nitrates.
• Mineral or vegetable oils, such as, for example, paraffin oil or caster oil, as well as silicone oil, can be used in the preparation of the emulsions employed according to the invention.
• Polyvinyl alcohol, methyl cellulose, vegetable gums, such as gum arabic which can be volatilized at moderate temperatures, for instance, can be employed as the binding agents.
• Ammonia is preferably employed as the alkaline medium but in some instances aqueous solutions of alkali metal hydroxides can be used, such as, for instance, in the production of zirconium oxide particles.
• the emulsifiers it is, of course, necessary that they be compatible with the salts and alkaline media concerned.
• nonionic emulsifiers are preferred, such as, for example, the polyoxyethylene esters of higher fatty acids, the alkyl phenyl polyethylene glycol ethers and polyoxyethylated fatty alcohols.
• the droplet size of the emulsion which is introduced into the alkaline medium for the production of the solid gelled spheres can, for instance, be preferably varied between and 5000
• the alkaline medium such as, for example, ammonia
• the alkaline medium such as, for example, ammonia
• immediate precipitation of, for example, the solid uranium compound is efiected in the suspended droplets.
• the quantity of metal salt contained in the emulsion introduced into the precipitating bath preferably is such as to provide 50 to 250 g. and expediently about 100 g. metal per liter of emulsion.
• Analogous results were obtained when the 400 ml. of paraffin oil were replaced by 400 ml. of caster oil or 350 ml. of silicone oil. Analogous results were also obtained when the PVA solution was replaced with 1 liter of a 2% methyl cellulose solution or 0.8 liter of a 10% gum arabic solution.
• Example 2 The procedure of Example 1 was repeated except that a mixed uranyl thorium nitrate solution was used instead of the uranyl nitrate solution so as to provide an emulsion containing 100 g. of U/Th per liter, 25 g. PVA per liter and a UzTh ratio of 1:10 and that a sintering temperature of 1150 C. was used.
• the resulting (U/Th) particles had a density which was 95% of theory.
• Example 3 The procedure of Example 2 was again repeated except that 21 g. of finely divided graphite were also suspended in the emulsion and a nitrogen atmosphere was used for the calcination and the sintering was carried out at 1800" C. to effect simultaneous sintering and conversion of the particles to U/Th carbide particles.
• Example 4 An emulsion prepared as described in Example 1 from an aqueous zirconyl chloride solution, paraffin oil and the emulsifier and after mixture with the PVA solution the mixture was introduced in droplet form into an aqueous 10% NaOH solution. The resulting freshly gelled spherical particles were washed and dried in air and then sintered at 1400 C. to dense ZrO particles.
• Example 5 An emulsion prepared as described in Example 1 from an aqueous aluminum hydroxy chloride solution, paraffin oil and the emulsifier and after mixture with the PVA solution the mixture (50 g. Al/ liter and 25 g. PVA/ liter) was introduced in droplet form into an aqueous NaOH solution. The resulting freshly gelled spherical particles were washed and dried in air and then sintered at 1400 C. to dense A1 0 particles.
• a method for the production of spherical particles of a material selected from the group consisting of metal oxides and metal carbides from aqueous metal salt solutions said metal being selected from the group consisting of uranium, thorium, zirconium and aluminum
• the steps of forming an emulsion of an aqueous solution of a salt of said metal which precipitates a solid compound when introduced into aqueous alkaline media and an oil and introducing said emulsion into an aqueous alkaline precipitating bath in the form of droplets to solidify such emulsion into completely reacted homogeneous particles.
• aqueous alkaline precipitating bath is selected from the group consisting of aqueous ammonia and aqueous alkali metal hydroxide solution.
• binding agent is selected from the group consisting of polyvinyl alcohol, methyl cellulose and vegetable gums.
• aqueous metal salt solution is an aqueous solution of at least one nitrate selected from the group consisting of uranyl and thorium nitrates.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Physics & Mathematics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Ceramic Engineering (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Dispersion Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Carbon And Carbon Compounds (AREA)

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Publications (1)

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Family Applications (1)

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Cited By (9)

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Citations (5)

• 1967
  • 1967-02-24 BE BE694642A patent/BE694642A/xx unknown
  • 1967-03-15 FR FR98927A patent/FR1515404A/fr not_active Expired
  • 1967-06-08 CH CH813467A patent/CH489444A/de not_active IP Right Cessation
  • 1967-06-09 NL NL676708065A patent/NL151638B/xx not_active IP Right Cessation
  • 1967-06-16 GB GB27884/67A patent/GB1193491A/en not_active Expired
  • 1967-07-05 US US651141A patent/US3535264A/en not_active Expired - Lifetime

Patent Citations (5)

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